Polypropylene composition for the production of high pressure pipes

Abstract

The present invention is directed to a polypropylene composition (C) applicable for the production of pressure pipes, said composition comprising a propylene random copolymer (rPP) and an impact modifier being a polyethylene (PE), as well as an article comprising said composition.

1 . A polypropylene composition (C), comprising
 i) 80.0 to 99.9 wt. % of a propylene random copolymer (rPP) comprising propylene and at least one comonomer being ethylene and/or a C 4 -C 8  α-olefin, said propylene random copolymer (rPP) having a melt flow rate MFR 2  determined according to ISO 1133 at 230° C. and a load of 2.16 kg in the range of 0.05 to 1.0 g/10 min, and   ii) 0.3 to 20.0 wt. % of a polyethylene (PE) having a density equal or below 940 kg/m 3 ,   based on the overall weight of the polypropylene composition (C).   
     
     
         2 . The polypropylene composition (C) according to  claim 1 , having a melt flow rate MFR 2  determined according to ISO 1133 at 230° C. and a load of 2.16 kg in the range of 0.05 to 1.0 g/10 min. 
     
     
         3 . The polypropylene composition (C) according to  claim 1 , having a Charpy Notched Impact Strength at 23° C. of at least 15.0 kJ/m 2 , determined according to ISO 179/1eA:2000. 
     
     
         4 . The polypropylene composition (C) according to  claim 1 , having a xylene cold soluble content (XCS) in the range of 1.0 to 15.0 wt. %, determined according to ISO 16152. 
     
     
         5 . The polypropylene composition (C) according to  claim 1 , wherein the ratio MFR(C)/MFR(rPP) is in the range of 0.8 to 1.3, wherein MFR(C) is the melt flow rate MFR 2  determined according to ISO 1133 at 230° C. and a load of 2.16 kg of the polypropylene composition (C) and MFR(rPP) is the melt flow rate MFR 2  determined according to ISO 1133 at 230° C. and a load of 2.16 kg of the propylene random copolymer (rPP). 
     
     
         6 . The polypropylene composition (C) according to  claim 1 , wherein the propylene random copolymer (rPP) has
 i) a comonomer content in the range of 1.0 to 15.0 mol % and/or   ii) a xylene cold soluble content (XCS) in the range of 1.0 to 15.0 wt. %, determined according to ISO 16152.   
     
     
         7 . The polypropylene composition (C) according to  claim 1 , wherein the propylene random copolymer
 i) has a melting temperature below 155° C. and/or   ii) is monophasic.   
     
     
         8 . The polypropylene composition (C) according to  claim 1 , wherein the propylene random copolymer (rPP) is at least bimodal. 
     
     
         9 . The polypropylene composition (C) according to  claim 8 , wherein the propylene random copolymer (rPP) is a bimodal propylene random copolymer (rPP-2) comprising:
 i) 35.0 to 55.0 wt. % of a first propylene random copolymer (rPP-2a), and   ii) 45.0 to 65.0 wt. % of a second propylene random copolymer (rPP-2b) which is different from the first propylene random copolymer (rPP-2a),   wherein the bimodal random copolymer (rPP 2) has an overall melt flow rate MFR 2  determined according to ISO 1133 at 230° C. and a load of 2.16 kg in the range of 0.01 to 5.0 g/10 min.   
     
     
         10 . The polypropylene composition (C) according to  claim 9 , wherein:
 i) the first propylene random copolymer (rPP-2a) has a comonomer content in the range of 1.0 to 5.0 mol %, and   ii) the bimodal random copolymer (rPP-2) has an overall comonomer content in the range of 3.0 to 10.0 mol %,   and wherein the first propylene random copolymer (rPP-2a) and the second propylene random copolymer (rPP-2b) are copolymers of propylene and ethylene and/or a C 4  to C 8  α-olefin.   
     
     
         11 . The polypropylene composition (C) according to  claim 8 , wherein the propylene random copolymer (rPP) is a trimodal propylene random copolymer (rPP-3) comprising:
 i) 30.0 to 50.0 wt. % of a first propylene random copolymer (rPP-3a),   ii) 42.0 to 60.0 wt. % of a second propylene random copolymer (rPP-3b) which is different from the first propylene random copolymer (rPP-3a), and   iii) 1.0 to 15.0 wt. % of a third propylene random copolymer (rPP-3c) which is different from the first propylene random copolymer (rPP-3a) and the second propylene random copolymer (rPP-3b),   wherein the overall melt flow rate MFR 2  determined according to ISO 1133 at 230° C. of the trimodal propylene random copolymer (rPP-3) is in the range of 0.1 to 3.0 g/10 min.   
     
     
         12 . The polypropylene composition (C) according to  claim 11 , wherein:
 i) the first propylene random copolymer (rPP-3a) has a comonomer content in the range of 1.0 to 4.9 mol %, and   ii) the trimodal propylene random copolymer (rPP-3) has an overall comonomer content in the range of 4.0 to 12.0 mol %,   wherein the propylene random copolymer (rPP-3a), the propylene random copolymer (rPP-3b) and the propylene random copolymer (rPP-3c) are copolymers of propylene and ethylene and/or a C 4  to C 8  α-olefin.   
     
     
         13 . The polypropylene composition (C) according to  claim 1 , wherein the propylene random copolymer (rPP) consists of a copolymer of propylene and ethylene. 
     
     
         14 . The polypropylene composition (C) according to  claim 1 , wherein the polyethylene (PE) has a melt flow rate MFR 2  determined according to ISO 1133 at 190° C. and a load of 2.16 kg in the range of 0.1 to 6.0 g/10 min. 
     
     
         15 . The polypropylene composition (C) according to  claim 1 , wherein the polyethylene (PE) is a low density polyethylene (LDPE). 
     
     
         16 . The polypropylene composition (C) according to  claim 1 , wherein the sum of the propylene random copolymer (rPP) and the polyethylene (PE) is at least 80 wt. %, based on the total amount of the polypropylene composition (C). 
     
     
         17 . An article comprising the polypropylene composition (C) according to  claim 1 . 
     
     
         18 . The article according to  claim 17 , wherein the article is a pipe.